|Author: || G. P. Blair |
|Title: ||Correlation of an Alternative Method for the Prediction of Engine Performance Characteristics with Measured Data|
|Date: || March 1993 |
|Published:|| SAE International Congress - Detroit, Michigan - SAE 930501 |
This paper presents confirmation of the accuracy of prediction of an engine simulation model. The
experimental data used to compare with the output of the simulation model are from a single cylinder
four-stroke cycle engine and from a single-cylinder two-stroke cycle engine; both engines are naturally
aspirated and use spark-ignition. In addition, for the two-stroke cycle engine, the experimental data
includes two cylinders with different scavenging characteristics which induce variations of performance
characteristics of up to 20%. The fundamentals of the theoretical approach have been presented before to
SAE and this paper extends that theory by providing a detailed discussion on the inclusion of measured
scavenging characteristics to enable the simulation model to predict the mechanism of the in-cylinder gas
exchange process. This permits the designer to use the simulation model to detail completely the internal
geometry of an engine, its port or valving, and its intake or exhaust ducting, and to deduce the overall
performance characteristics such as power, torque, airflow or fuel consumption. Further detailed
information is presented from the use of the simulation model on scavenging, trapping, and charging
efficiencies and delivery ratio and also the pressures, temperatures, particle velocities, charge purities
and densities as a function of time in various location throughout the engine. Such detailed insights into
the internal gas dynamic and gas exchange characteristics are invaluable in that many are almost impossible
to acquire experimentally and so they given the designer a "feel" for the engine behavior which could not
otherwise be obtained.
The level of accuracy of correlation between measurement and calculation is such that the model can be used
for design purposes with considerable confidence.
You may obtain a copy of this paper by calling SAE Customer Service at 1-877-606-7323 (toll-free in the U.S. and Canada) or 1-724-776-4970.